One hundred fifty years after its creation, New York City's Central Park caters to a multitude of visitors with diverse interests - from exercise and entertainment to courtship and simple people watching. But everyone, it seems, loves Central Park most for its captivating natural beauty. There are many good ways to appreciate Central Park and its natural gifts: poetically - as an island of living emerald in a sea of concrete and gray; and spiritually - as a refuge for contemplation and communion. Biologically, Central Park is home to a amazing assortment of plants and animals.

According to a recent survey of the Park's flora and fauna, there at least 835 species of plants, mammals, birds, bugs, fish, assorted invertebrates, spiders, turtles, snails, and other living things.

Enjoying this natural bounty is a regular pastime for Lynn and Dick, an older couple sitting on a park bench on a recent sunny afternoon.

"It's just exciting because you come from the sounds of ambulances, the hectic pace, concrete, steel and you come into the park and you come into the trees and these beautiful birds flying," said Lynn.

At the moment, Lynn and Dick are gazing up at a pair of red-tailed hawks feeding their young in a nest under the eaves of a Fifth Avenue apartment just across from the Park.

"We moved to the area just a few blocks away and discovered the excitement of people watching these hawks through these huge telescopes," she said.

"There are two babies chicks in the nest at this time. It's nature at its rawest," added Dick.

Rick Davis, an urban naturalist, has set up a telescope so passersby can watch these red-tailed hawks go about their lives.

"This the first reproducing nest of red-tailed hawks in Manhattan in 100 years. The male is called 'Pale Male.' He came in and started the whole thing. And he has had about 22 successful children over the years. Two this year," he said.

Mr. Davis explains why Central Park can be an easier place to observe hawks and other birds than in the wild.

"Well, we have access to them. They are used to people and us. If you were in the wild you could not get anywhere near these hawks like we do. They treat us just like other animals that aren't going to bother them, which red tails in the wild do not do. It's very exciting. I've seen them catch a rat 10 feet away from me," he said.

Achieving a proper balance between humans and non-humans in New York's favorite park can be difficult. The actor David Constabile remembers meeting a raccoon in his dressing room moments before performing in a Shakespeare play on one of Central Park's open-air stages.

"I was changing my clothes the other night, it's down underneath the stage, and the raccoon is just looking at me," he recalled. "Four feet [about 1 1/3 meters] away from me. And I'm, like 'Go away! It's time for me to change my clothes and it's time for you not to be here!' The raccoon luckily got scared and walked away. It's fun because it makes it really feel live!"

Over 15 million visitors a year can take a toll on the plant and animal habitats of Central Park no matter how hardy they are. Neal Calvanese directs the department responsible for making sure the Park's 340 hectares remain green, healthy and accessible.

"A lot goes into it to make sure it does stay green because when you have the volumes of people we do, the impact is tremendous on the soil. And we really have to keep up with it: over-seeding, replanting, taking care of plants that are stressed because of all the people," he said. "It is a balance we're trying to strike. Let's say we are doing a tree removal, one of the things we will look at is, is that tree providing habitat for wildlife? And if so, how can we make the tree safe yet keep the habitat there? And we do that all the time."

The land where New York City now stands was once part of a vast tract of deciduous forest that served as a habitat for thousands of native species. And while the land where Central Park itself came to be was originally a thinly-populated ecosystem, efforts are now under way to introduce or reintroduce - plants and animals that might have lived in the area long ago.

"We are not trying to bring back poison ivy, rattlesnakes or wolves. But we are looking to reintroduce things like chipmunks, cottontail rabbits, and we have already done screech owls," said Alexander Brash, chief of the Urban Park Ranger Service, which helps with the project. "We target species that we know are not going to present any potential harm to the patrons of the Park and which we think will be a key building block to either something like a predator-prey cycle, [or] maybe they are a necessary pollinator for some of the Park's plants. They might even be a seed-disperser or indeed something that might be esthetically very pleasing and [which' we think contribute not only to enjoyment of the park but also [to] the education to the Park's patrons and New York City's kids."

One man who has been educating New York children and their parents for decades is "Wildman" Steve Brill. He conducts tours through Central Park in search of wild and edible plants.

"Herbs, beans, berries, nuts, seeds, roots, mushrooms, renewable resources, things that you can harvest that just grow back again. Things people call weeds that our ancestors have been using for thousands of years for food and home remedies," he explained.

With "the Wildman's" help, a tour group has found wild sarsaparilla, which tastes like root beer and purportedly cleans the blood; sheep sorrel, a tasty salad green; and mulberries, which are soft and sticky and good as a sweet dessert. The Wildman makes an announcement before lunch.

"That's the boathouse, when we take our lunch break you can take the sidewalk, walk over to the boathouse, and you'll find the rarest species in Central Park: the working restroom," he joked.

It's an urban jungle out there. But you won't find New Yorkers complaining about it - at least when it comes to their beloved Central Park.